SR-71 Blackbird
Please note: This plane requires VIP to spawn. Courtesy of Cheeseycrackers100 for images. Background Lockheed's previous reconnaissance aircraft was the relatively slow U-2, designed for the Central Intelligence Agency (CIA). In late 1957, the CIA approached the defense contractor Lockheed to build an undetectable spy plane. The project, named Archangel, was led by Kelly Johnson, head of Lockheed's Skunk Works unit in Burbank, California. The work on project Archangel began in the second quarter of 1958, with aim of flying higher and faster than the U-2. Of 11 successive designs drafted in a span of 10 months, "A-10" was the front-runner. Despite this, however, its shape made it vulnerable to radar detection. After a meeting with the CIA in March 1959, the design was modified to have a 90% reduction in radar cross-section. The CIA approved a US$96 million contract for Skunk Works to build a dozen spy planes, named "A-12" on 11 February 1960. The 1960 downing of Francis Gary Powers's U-2 underscored its vulnerability and the need for faster reconnaissance aircraft such as the A-12. The A-12 first flew at Groom Lake (Area 51), Nevada, on 25 April 1962. Thirteen were built; two variants were also developed, including three of the YF-12 interceptor prototype, and two of the M-21 drone carrier. The aircraft was meant to be powered by the Pratt & Whitney J58 engine, but development ran over schedule, and it was equipped instead with the less powerful Pratt & Whitney J75 initially. The J58s were retrofitted as they became available, and became the standard powerplant for all subsequent aircraft in the series (A-12, YF-12, M-21), as well as the SR-71. The A-12 flew missions over Vietnam and North Korea before its retirement in 1968. The program's cancellation was announced on 28 December 1966,11 due both to budget concerns and because of the forthcoming SR-71, a derivative of the A-12. ENGINES The SR-71 was powered by two Pratt & Whitney J58 (company designation JT11D-20) axial-flow turbojet engines. The J58 was a considerable innovation of the era, capable of producing a static thrust of 32,500 lbf (145 kN). The engine was most efficient around Mach 3.2, the Blackbird's typical cruising speed. At lower speeds, the turbojet provided most of the compression. At higher speeds, the engine largely ceased to provide thrust, the afterburner taking its place. Air was initially compressed (and heated) by the inlet spike and subsequent converging duct between the center body and inlet cowl. The shock waves generated slowed the air to subsonic speeds relative to the engine. The air then entered the engine compressor. Some of this compressor flow (20% at cruise) was removed after the fourth compressor stage and went straight to the afterburner through six bypass tubes. The air passing through the turbojet was compressed further by the remaining five compressor stages and then fuel was added in the combustion chamber. After passing through the turbine, the exhaust, together with the compressor bleed air, entered the afterburner. At around Mach 3, the temperature rise from the intake compression, added to the engine compressor temperature rise, reduced the allowable fuel flow because the turbine temperature limit did not change. The rotating machinery produced less power, but still enough to run at 100% RPM, thus keeping the airflow through the intake constant. The rotating machinery had become a drag item and the engine thrust at high speeds came from the afterburner temperature rise. Maximum flight speed was limited by the temperature of the air entering the engine compressor, which was not certified for temperatures above 800 °F (430 °C). Originally, the Blackbird's J58 engines were started with the assistance of two Buick Wildcat V8 internal combustion engines, externally mounted on a vehicle referred to as an AG330 "start cart". The start cart was positioned underneath the J58 and the two Buick engines powered a single, vertical drive shaft connecting to the J58 engine and spinning it to above 3,200 RPM, at which point the turbojet could self-sustain. Once the first J58 engine was started, the cart was repositioned to start the aircraft's other J58 engine. Later start carts used Chevrolet big-block V8 engines. Eventually, a quieter, pneumatic start system was developed for use at the main operating bases. The V8 start carts remained at diversion landing sites not equipped with the pneumatic system. TITANIUM BUILD & STEALTH Titanium was in short supply in the United States, so the Skunk Works team was forced to look elsewhere for the metal. Much of the needed material came from the Soviet Union. Colonel Rich Graham, SR-71 pilot, described the acquisition process: The airplane is 92% titanium inside and out. Back when they were building the airplane the United States didn't have the ore supplies – an ore called rutile ore. It's very sandy soil and it's only found in very few parts of the world. The major supplier of the ore was the USSR. Working through Third World countries and bogus operations, they were able to get the rutile ore shipped to the United States to build the SR-71. LIFE SUPPORT Flying at 80,000 ft (24,000 m) meant that crews could not use standard masks, which could not provide enough oxygen above 43,000 ft (13,000 m). Specialized protective pressurized suits were produced for crew members by the David Clark Company for the A-12, YF-12, M-21, and SR-71. Furthermore, an emergency ejection at Mach 3.2 would subject crews to temperatures of about 450 °F (230 °C); thus, during a high-altitude ejection scenario, an onboard oxygen supply would keep the suit pressurized during the descent. The cockpit could be pressurized to an altitude of 10,000 or 26,000 ft (3,000 or 8,000 m) during flight. The cabin needed a heavy-duty cooling system, as cruising at Mach 3.2 would heat the aircraft's external surface well beyond 500 °F (260 °C) and the inside of the windshield to 250 °F (120 °C). An air conditioner used a heat exchanger to dump heat from the cockpit into the fuel prior to combustion. The same air-conditioning system was also used to keep the front (nose) landing gear bay cool, thereby eliminating the need for the special aluminum-impregnated tires similar to those used on the main landing gear. Blackbird pilots and RSOs were provided with food and drink for the long reconnaissance flights. Water bottles had long straws that crewmembers guided into an opening in the helmet by looking in a mirror. Food was contained in sealed containers similar to toothpaste tubes which delivered food to the crewmember's mouth through the helmet opening.